1. Field of the Invention
This invention relates generally to metallized films and, more particularly, to metallized polyurethane films. This invention also relates to decorative articles made with such metallized films.
2. Description of the Related Art
Metallized films, that is, films comprising a polymeric substrate on which has been deposited a layer of metal, are often employed in, for example, the automotive, furniture, stationery, interior building material, and advertising industries to provide an aesthetic or decorative enhancement to manufactured articles. Such films, in order to be commercially useful as decorative and aesthetic enhancements, should possess several characteristics.
For example, the substrate layer should be highly transparent so as not to detract from the reflective quality of the metal layer and the overall appearance of the article. The films should also exhibit good heat stability, especially when employed in the construction of outdoor signs, motor vehicles and other articles where high temperatures may be encountered. For example, the interior of a motor vehicle on a warm, sunny day in certain climates may experience temperatures in excess of 90xc2x0 C.
Flexibility is another desirable quality because flexible films are more readily applied to rough or uneven surfaces and multifaceted articles having a compound geometry. In still other applications, metallized films may be embellished with printed messages, decorative patterns, or complementary, decorative, transparent, colored layers. Metallized films, in order to be commercially useful, should readily accept printing and should be susceptible to the adhesion of further decorative layers thereto. Such films should also possess excellent adhesion between the metal and substrate layers. The films should be capable of being applied in an economical manner and retain a quality appearance without developing bubbles, wrinkles, swells or the like. Once applied, the film, should remain durable and exhibit good resistance to a wide variety of weathering and environmental conditions.
Metallized films that display a bright, highly polished, highly reflective mirrorlike appearance would be especially desirable if they could be bonded to a reinforcing layer since they could be used to simulate conventional chrome plated components, such as are found on motor vehicles.
Various metallized films are presently known. For example, metallized polyester films have been commercially available for many years.
U.S. Pat. No. 5,164,245 (Suzuki) discloses a metallized multilayer film comprising a first substrate layer, a second substrate layer on the first substrate layer, and a layer of metal on the second substrate layer. The first substrate layer comprises from 0 to about 40 parts by weight poly(vinylidine fluoride) and, correspondingly, from 100 to about 60 parts by weight poly(methyl methacrylate). This patent reports that metallized acrylic films are also known.
U.S. Pat. No. 4,101,698 (Dunning et. al.) discloses a transfer laminate having a flexible transparent or translucent elastomeric layer (e.g., polyurethane) and a layer of metal bonded to the elastomeric layer in separate, microscopically discontinuous planar quantities of high reflectivity. The metal layer forms an apparent visually continuous reflective surface.
This invention relates to metallized films that comprise an opaque, continuous layer of metal in direct contact with an aliphatic polyurethane substrate. The polyurethane substrate displays a glass transition temperature of about 25 to 110xc2x0 C. and a melting temperature greater than or equal to 200xc2x0 C. The metal layer may be tin, chromium, nickel, stainless steel, copper, aluminum, indium, gold, silver, or alloys thereof.
The polyurethane substrate may be derived from an aqueous urethane dispersion and may advantageously include a small amount of a crosslinking agent to desirably shift or provide the the glass transition temperature and/or to shift the melting temperature.
Other optional, though highly desired, layers that may form a part of the metallized film include a primer for improving the adhesion between the metal layer and a subsequent surface. The metallized films may also include a color layer on the polyurethane substrate and a protective clear coat layer on the color layer.
Various decorative articles including multifaceted articles having a compound geometry may be made using the metallized films of the invention. The metallized film may be placed in a conventional vacuum forming mold and a polymeric reinforcing layer may be added thereto. Attachment of the resulting decorative article to a subsequent surface may be facilitated by the use of an adhesive on the reinforcing layer.
Decorative articles made with the metallized films of the invention simulate the appearance of conventional chrome plated parts.